An ethylometer is a device for measuring the ethyl alcohol content in the blood, broadly used by law enforcement agencies, above all to check motorists suspected to be in a state of inebriation. This device can comprise a chemical composition capable of changing color in the presence of alcohol vapors. By checking the exhaled breath, in fact, it is possible to understand if an individual has ingested beverages containing ethanol, and whether the intake is higher or lower than the safety values established by the highway code. The operating principle of an ethylometer is based on the fact that, after being ingested, alcohol is rapidly absorbed by the stomach and intestine and is mostly metabolized in the body. A small part, however, is eliminated through urine, sweat and breath. The latter part is what is in practice detected during an alcohol test by means of the composition contained in the ethylometer. Among the common commercially available ethylometers, there exist some of them comprising compositions based on chromium salts, typically dichromate, and/or iodine salts capable of changing color if placed in contact with alcohol vapors.
Patent ITPG20040047, for example, describes in general terms an alcohol testing device which exploits the chromatic properties of a composition comprising an iodine salt, a catalyst in the form of nitrate ions and phosphoric acid- and sulphuric acid-impregnated silica. This mixture, however, requires a laborious and costly process of preparation, which also includes a step of boiling the silica in sulphuric acid.
Moreover, the biggest problem of the compositions generally used in ethylometers is the fact that they are not capable of a long maintaining of the color appearing after the test was performed, and which is indicative of the positive test result. Moreover, the testing rate and the sensitivity to alcohol vapors are often low, so that they are not recommended for a practical and reproducible use.
There thus remains a need to find a composition that is useful for the detection of alcohol vapors in air samples, and which enables the color to be maintained substantially unchanged also for a long time, at the same time ensuring high sensitivity, and rapid response rate.